nginx

The configuration templates shown below apply to both single-application and domain-level forward auth.

info

example-outpost is used as a placeholder for the outpost name. authentik.company is used as a placeholder for the authentik install. app.company is used as a placeholder for the external domain for the application. outpost.company is used as a placeholder for the outpost. When using the embedded outpost, this can be the same as authentik.company

Standalone nginx
Ingress
Nginx Proxy Manager

server {
    # SSL and VHost configuration
    listen                  443 ssl http2;
    server_name             _;

    ssl_certificate         /etc/ssl/certs/ssl-cert-snakeoil.pem;
    ssl_certificate_key     /etc/ssl/private/ssl-cert-snakeoil.key;

    # Increase buffer size for large headers
    # This is needed only if you get 'upstream sent too big header while reading response
    # header from upstream' error when trying to access an application protected by goauthentik
    proxy_buffers 8 16k;
    proxy_buffer_size 32k;

    location / {
        # Put your proxy_pass to your application here, and all the other statements you'll need
        # proxy_pass http://localhost:5000;
        # proxy_set_header Host $host;
        # proxy_set_header ...

        ##############################
        # authentik-specific config
        ##############################
        auth_request     /outpost.goauthentik.io/auth/nginx;
        error_page       401 = @goauthentik_proxy_signin;
        auth_request_set $auth_cookie $upstream_http_set_cookie;
        add_header       Set-Cookie $auth_cookie;

        # translate headers from the outposts back to the actual upstream
        auth_request_set $authentik_username $upstream_http_x_authentik_username;
        auth_request_set $authentik_groups $upstream_http_x_authentik_groups;
        auth_request_set $authentik_email $upstream_http_x_authentik_email;
        auth_request_set $authentik_name $upstream_http_x_authentik_name;
        auth_request_set $authentik_uid $upstream_http_x_authentik_uid;

        proxy_set_header X-authentik-username $authentik_username;
        proxy_set_header X-authentik-groups $authentik_groups;
        proxy_set_header X-authentik-email $authentik_email;
        proxy_set_header X-authentik-name $authentik_name;
        proxy_set_header X-authentik-uid $authentik_uid;
    }

    # all requests to /outpost.goauthentik.io must be accessible without authentication
    location /outpost.goauthentik.io {
        proxy_pass              http://outpost.company:9000/outpost.goauthentik.io;
        # ensure the host of this vserver matches your external URL you've configured
        # in authentik
        proxy_set_header        Host $host;
        proxy_set_header        X-Original-URL $scheme://$http_host$request_uri;
        add_header              Set-Cookie $auth_cookie;
        auth_request_set        $auth_cookie $upstream_http_set_cookie;
        proxy_pass_request_body off;
        proxy_set_header        Content-Length "";
    }

    # Special location for when the /auth endpoint returns a 401,
    # redirect to the /start URL which initiates SSO
    location @goauthentik_proxy_signin {
        internal;
        add_header Set-Cookie $auth_cookie;
        return 302 /outpost.goauthentik.io/start?rd=$request_uri;
        # For domain level, use the below error_page to redirect to your authentik server with the full redirect path
        # return 302 https://authentik.company/outpost.goauthentik.io/start?rd=$scheme://$http_host$request_uri;
    }
}

Create a new ingress for the outpost

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
    name: authentik-outpost
spec:
    rules:
        - host: app.company
          http:
              paths: /outpost.goauthentik.io
              pathType: Prefix
              backend:
                  # Or, to use an external Outpost, create an ExternalName service and reference that here.
                  # See https://kubernetes.io/docs/concepts/services-networking/service/#externalname
                  service:
                      name: ak-outpost-example-outpost
                      port:
                          number: 9000

This ingress handles authentication requests, and the sign-in flow.

Add these annotations to the ingress you want to protect

metadata:
    annotations:
        # This should be the in-cluster DNS name for the authentik outpost service
        # as when the external URL is specified here, nginx will overwrite some crucial headers
        nginx.ingress.kubernetes.io/auth-url: |-
            http://ak-outpost-example.authentik.svc.cluster.local:9000/outpost.goauthentik.io/auth/nginx
        # If you're using domain-level auth, use the authentication URL instead of the application URL
        nginx.ingress.kubernetes.io/auth-signin: |-
            https://app.company/outpost.goauthentik.io/start?rd=$escaped_request_uri
        nginx.ingress.kubernetes.io/auth-response-headers: |-
            Set-Cookie,X-authentik-username,X-authentik-groups,X-authentik-email,X-authentik-name,X-authentik-uid
        nginx.ingress.kubernetes.io/auth-snippet: |
            proxy_set_header X-Forwarded-Host $http_host;

For Nginx Proxy Manager you can use this snippet

# Increase buffer size for large headers
# This is needed only if you get 'upstream sent too big header while reading response
# header from upstream' error when trying to access an application protected by goauthentik
proxy_buffers 8 16k;
proxy_buffer_size 32k;

# Make sure not to redirect traffic to a port 4443
port_in_redirect off;

location / {
    # Put your proxy_pass to your application here
    proxy_pass          $forward_scheme://$server:$port;
    # Set any other headers your application might need
    # proxy_set_header Host $host;
    # proxy_set_header ...

    ##############################
    # authentik-specific config
    ##############################
    auth_request     /outpost.goauthentik.io/auth/nginx;
    error_page       401 = @goauthentik_proxy_signin;
    auth_request_set $auth_cookie $upstream_http_set_cookie;
    add_header       Set-Cookie $auth_cookie;

    # translate headers from the outposts back to the actual upstream
    auth_request_set $authentik_username $upstream_http_x_authentik_username;
    auth_request_set $authentik_groups $upstream_http_x_authentik_groups;
    auth_request_set $authentik_email $upstream_http_x_authentik_email;
    auth_request_set $authentik_name $upstream_http_x_authentik_name;
    auth_request_set $authentik_uid $upstream_http_x_authentik_uid;

    proxy_set_header X-authentik-username $authentik_username;
    proxy_set_header X-authentik-groups $authentik_groups;
    proxy_set_header X-authentik-email $authentik_email;
    proxy_set_header X-authentik-name $authentik_name;
    proxy_set_header X-authentik-uid $authentik_uid;
}

# all requests to /outpost.goauthentik.io must be accessible without authentication
location /outpost.goauthentik.io {
    proxy_pass              http://outpost.company:9000/outpost.goauthentik.io;
    # ensure the host of this vserver matches your external URL you've configured
    # in authentik
    proxy_set_header        Host $host;
    proxy_set_header        X-Original-URL $scheme://$http_host$request_uri;
    add_header              Set-Cookie $auth_cookie;
    auth_request_set        $auth_cookie $upstream_http_set_cookie;
    proxy_pass_request_body off;
    proxy_set_header        Content-Length "";
}

# Special location for when the /auth endpoint returns a 401,
# redirect to the /start URL which initiates SSO
location @goauthentik_proxy_signin {
    internal;
    add_header Set-Cookie $auth_cookie;
    return 302 /outpost.goauthentik.io/start?rd=$request_uri;
    # For domain level, use the below error_page to redirect to your authentik server with the full redirect path
    # return 302 https://authentik.company/outpost.goauthentik.io/start?rd=$scheme://$http_host$request_uri;
}